Electric railway system



March 12, 1929. I w c 1,704,958

ELECTRIC RAILWAY SYSTEM Filed Jan. 1927 Patented Mar. 12, 1929.

UNITED STATES PATENT oF-F'IcE;

ALFRED WIGHERT, OF MANNI-IEIM-NEUOSTHEIM, GERMANY, ASSIGNOR TO AKTIEN- GESELLSOHAFT BROWN BOVERI & GIE., OF BADEN, SWITZERLAND, A JOINT-STOCK COMPANY.

Application filed January 6, 1927, Serial No.

. My invention relates to electric railway systems, and it has particular relation to systems utilizing combined adhesion and rack drives. p 1

In the operation of railroads extendingin part over level road stretches, and in part over heavy grade stretches, it has been customary to use locomotives, or vehicles, having a combined adhesion drive and rack drive. The adhesion drive is principally used over the level stretches of the road, while the rack drive supplies the main part of the propelling power over the inclined stretches of the road. For the satisfactory operation of such railways,-it is of utmost importance to insure smooth transition from the adhesion to the rack sections of the railway at all practical speeds, and to eliminate sudden shocks when the toothed wheel enters the rack section at the beginningof a heavy grade in the road.

Among the objects of the present invention is the provision of an electric railway system of the foregoing character in which the adhesion'motor and: rack motors are. so interconnected as to insure smooth transition of locomotives, or vehicles, from one section of the road to the other. A particular object of the invention is the arrangementof the forego ing character for use inconnection with the drives employing a plurality of rack motors.

vAccording to the invention. the co-ordin'ation of the speeds of the'adhesion and rack motors is obtained by connecting the adhesion motor in series withfield'windings of the rack motors. In order to prevent unbalance of current between the armatures of the rack motors, which are usually connectedin parallel, the latter motors are provided with a second set of field windings whichare connected in series with their armatures. This arrangement secures correct relationship be tween the speedsof the two sets of motors un-. der all conditions of operation, indirect response. to the tractiveetlorts to be exercised by the two sets of motors. At the same time, correct current balance between the several motorsis obtained. y

In the accompanying drawings illustrating an exemplification of theinvention, r

Fig. 1 is an elevational View of anelectric locomotive embodying the invention; and

. Fig. 21s a circuit diagram of the locomotive drive showninFig. 1. p I

ELECTRIC RAILWAY SYSTEM.

159,430, and in Germany January 11,1926.

' hesion drivell for propelling the locomotive over level sections of the road, anda rack drive 12 for. propelling the locomotive over I steep grades of the road. The adhesion drive comprises the locomotive wheels 13 arranged I l to run along the rails 14 in the customary Way, the locomotive wheels. being rotated. by

an adhesion motor 15 through the interme-- diary of a gear mechanism 16 and a driving rod 17 The rack drive comprises a rack 21 extending parallel to the rails 14 over the steep sectlons of the road.. Suitable gear:

wheels 22 engage the rack 21 and are rotated thereon bymeans of a pair of rack motors 23, 24;. The rack motors impart rotation to the gear wheels 22 through an intermediary mechanism 25 comprising pinions 26 mounted on the motor shafts and a common gear wheel 27 driven thereby.

The adhesionmotor 15 and the rack motors 23, 24, of the locomotive shown in the draw- 1 ing, areof the direct-current type, and are 7 supplied-withenergy from an overhead trolley line 28in a'customary manner.

,For the successful operation of railroads of theforegoing character, it is important i that the .speed of the gear wheels 22 ofthe rack drive shall be maintained in' a definite relation to the speed impartedto the locomo-:

tive by thegadhesion drive, in particular,

when the locomotive is about to leave a'level I road section in which it was propelledby adhesion alone, and is to enter a steep road section in which the rack drive is to become effective. If the speed of the rack wheel 22 differs, appreciably from the speed corre-Y sponding to the locomotive speed, a considerable shockwill be exerted on the rack and the rack drive of the locomotive. Under such conditions the. locomotive and the road will very soon be damaged or require excessive maintenance. i I

The present invention avoids the'difficulties that may. result from lack of co-ordina tion between. the adhesionand rack drives by suitable connections between the two sets of driving motors. To this end, when the locomotive is to enter a rack section, thecurrent from the adheslon motor is lead through the field of the unloaded rack motor'during the period of transition. By suitable shunt connections in the field windings the speed characteristics of the adhesion motor andxthetunloaded rack' motor can be so ad justed thatthe speedsof the two drives are in perfect agree ment. llnder suchconditionsthere will be noshocikon.enteringlth-e rack section.

"The "foregoing system of connections is practicable however, only when asingle Incl:

10 motor is used. If there are several rack motors adapted :;to operate in parallel, asystem of connections described above gives diflicultiesion-accountefthe poor-distribution oii-the --cur-rent 'between the several motors. The

poor current distribution is a direct result of thedifl'erence in the speed characteristics of twootherwise similar motors, these differences in the speed characteristics being large- 'ly .due to difierences inthe field fluxes which BJFGQPIGSGIHBIBVBII in case of two-similarly constructed-motors. =Whentwo such motors are arranged to operate a rack drive, such .as shown in Fig. l,the armaturesare-connected iBLPitlfHiLh-Kl and the field windings of the :two

motors areconnected in'series and traversed byzthescurrent from-the adhesion motor; reason of the common gear wheel 25 of @the gear mechanism by which the atwo motors areicoupled to thew-heel 22, both motorsmust maintain the same speed." Under such con ditionsaeven slight differences in the v field stnuctnres oil? the :two motors will produce large differences in the electro-motive iforce I 5 of the armatures and result in an unequaljdi$- tribution of :the current between 'tl16"a'1IIl2ttitres; Very slight differences in the *field structures will then cause vary heav-y current unbalance between the armatures and cause very often excessivesparking in thecoinlnu- 4.0 tuitorsiand seriously impair the operativeness oifz the system.

According to the invention the last men tioned difficulties are avoided, and unequal loading of the motors eliminated by providingizeach of the rack motors with two setsof field :windings. One set of field windings is connected in series :to receive current from the adhesive motor, while each winding of theother-set is connectedwith the associated alunature winding of'the respective rack'motor.

llihissystem of connection is shown in diagramin Fig; 2. a The adheslon motor 1'5-CGII14 prises Jan armature 3-1 with a. field winding 32,:whlileseach of the-rackniotors, 23,24, co1nprisesan armature 33 w itha serially connectedfield winding element 34, and an additional lfie'ld winding element 35. The field winding 1:32and the armature 81 of the adhesion linotor are connected in series with the two serial'lyiconnected additional w'inding elements 35 a of the rack motors between the trolley28and the return rail 29,.respecti-vel y. liheiazrmatures .33'of the two rack meters are each iconnected'in series withthe associated field windings 34: and the two sets of armature and field windings are supplied in parallel from the {trolley 28 and return rail 29.- By Ineansofa resistor 36 connected in sl-i-unt-tothe field winding 32 of the adhesion, linotor, the speed of the two sets -.oi?-;n1otors may readily he so adjusted that the speed ofthe rack wheel 22 corresponds-exactly to the walllo iatrmhich it will run into the rack without a shock. By suitable control of the shunt resistor.36.the -load inaythenibe transferred to the rack motors. V V

'Thetforegoing system of connections efiectively prevents current unbalance bet'weeen the parallel connected rack-motor armatures. Thus, for instance, assumingthat the speed characteristics of the two mOto-rs are different anid that one of the motors, namely, motor--23, has-a -wealter field,=t-he far-mature of this motor will tend *to take a :larger current than "the other-parallel-connected armature of the motor 24. However, an increaseof the current "through the armature of the'motor 23 will -innnedia-te'ly increase the flux produced *hy the associated serially connected yv field winding34ythus eounteracting'thetendency to take "more current than the other armature. V

The fore'going system of conneetronslthus gives good current balanceibetween theparail lel-opera'ting motors "despite differences in r the speedcharacteristics of the same.

invention is susceptible of :many inodh. fications other thanthat specifically described in *the specification. For-instance, a darger nunoiberott motors thanshown i-n-the drawings may-be used,and-insteadottoneradhesionniotor, sever'zvl nay be used, properzprovlsion -belng made, fliowever,--to secure suitable current distribution betWeeirtl-ie several motors. In; stead of having all; (if a the current from the adhesion --1noters passing through the series field windings 35'01Efl1h61'8i0k motors, only a part thereof-may 'be passed 'therethrongh as, for instance, by p rov-i'di-ng a shunt '39 in-parslid to the two serial ly-conneetedfield wind" ings "35.

'1 dl ai-m-as my invention:

l; In an electric railway system utilizing conihined adhesion and *rackdrives, an "ad hesion motor, a rack-motor having afield w i nding "element, means tor connecting the adhesion metorand said element in series to a-sou-reeo-t supply, and means iforind-ependent'ly connecting the armature of the rack motor parallel relation with respect to the series comprising said adhesionmotor and saidelement. V r r 2. In an electric railway system utilizing combined-adhesion and rack drives, an ad hesion motorand apluraiityof-rack motors, each of said rack --1notors comprising two sets of field windings, the field windings of one setlbeing connected in series, means for supplying the field windings otone set with -current from the adhesion motor, and means for supplying the field windings of the other set with current from their respective armatures.

3. In an electric'railway system utilizing combined adhesion and rack drives, a directcurrent motor system comprising an adhesion motor and a plurality of rack motors, each of said rack motors having two field-winding elements, means for causing one field winding element of each rack motor to be traversed by the current of the adhesion motor, and means for causing the other winding element of each rack motor to be traversed by the armature current of said motor.

4. A control system for direct-current driven rail vehicles having separate adhesion and rack driving motors in which the current passing through the armature of the adhesion motor is used to excite the field of the rack motors, characterized by the fact that the rack motors have two sets of field windings, one set of field windings being excited by current from the adhesion motorand the other set of field windings being supplied.

with current from the respective armatures with which they are associated.

5. In an electric railway system utilizing adhesion and rack drives, an adhesion motor, a plurality of rack motors each having a first and a second set of field windings, means pro viding for connection of the windings comprising the first set in series with respect to each other and to said adhesion motor, and means providing for connection of the windings comprising the second set in such manner that the same constitute series fields respectivelyfor said rack motors, said second means providing for parallel operation of said rack motors.

In testimony whereof I have hereunto subscribed my name at Berlin on the18th day of December, A. D. 1926.

ALFRED WICHERT. 

